Vessel exhaust gas denitration system and method of determining nozzle clogging in the same

ABSTRACT

Provided are an exhaust gas vessel denitration system and a method of determining nozzle clogging in the same, and more particularly, an exhaust gas vessel denitration system including an exhaust pipe for discharging exhaust gas including nitrogen oxide generated from an engine of a vessel, a reducing agent inlet configured as an integrated dosing unit (IDU) for injecting a reducing agent into the exhaust pipe, and a reactor for inducing a reduction reaction of exhaust gas mixed with the reducing agent and decomposing nitrogen oxide in the exhaust gas to nitrogen and water vapor to reduce the nitrogen oxide, and a method of determining clogging of urea spray at an injector nozzle of the system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2017-0161963, filed on Nov. 29, 2017, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The following disclosure relates to an exhaust gas vessel denitrationsystem and a method of determining nozzle clogging in the same.

BACKGROUND

Recently, internationally, regulations for environmental pollution havebecome stricter, and new conventions have been enacted and adopted toregulate the emission of air pollutants from ships.

International Maritime Organization (IMO) amends the Marine PollutionTreaty (MARPOL IV)' to propose tighter nitrogen oxide (NOx) regulationson discharge (Tier III) in the 62^(nd) Marine Environment ProtectionCommittee (MEPC) in July, 2011 and effectuates the regulations on Jan.1, 2016.

Accordingly, exhaust gas denitration equipment needs to be installed inan engine of a newly constructed vessel to permit the vessel to sail inthe Emission Control Area (ECA). Thus, an exhaust gas vessel denitrationsystem is essential for a vessel.

SUMMARY

An embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system and a method of determining nozzleclogging in the same, for simplifying a structure of an exhaust gasvessel denitration system of a vessel using selective catalyst reduction(SCR) and reducing an installation space in the vessel. Moreparticularly, the present disclosure is directed to an exhaust gasvessel denitration system including an exhaust pipe for dischargingexhaust gas including nitrogen oxide generated from an engine of avessel, a reducing agent inlet configured as an integrated dosing unit(IDU) for injecting a reducing agent into the exhaust pipe, and areactor for inducing a reduction reaction of exhaust gas mixed with thereducing agent and decomposing nitrogen oxide in the exhaust gas tonitrogen and water vapor to reduce nitrogen oxide, and a method ofdetermining clogging of urea spray at an injector nozzle of the system.

Another embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system and a method of determining nozzleclogging in the same, for simply omitting components such as a flow ratecontrol valve and various gages accompanied thereby and controllingeffective urea spray by forming a reducing agent inlet for injecting areducing agent as an integrated dosing unit (IDU) formed by integratinga pump for supplying urea via control of a rotation number and aninjecting module using pulse spray.

Another embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system and a method of determining nozzleclogging in the same, for supplying and spraying a fixed amount of ureaand rapidly and accurately determining whether a nozzle clogs byperiodically controlling a pump rotation number and opening and closingof a pulse injector.

Another embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system and a method of determining nozzleclogging in the same, for cooling a pulse injector included in aninjecting module of a reducing agent inlet by compressed air to preventthe injecting module from being damaged by heat during heating of thecompressed air.

Another embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system including a catalyst, which iscapable of being miniaturized to ensure economic efficiency through ahigh specific surface area while maintaining advantages of a metalliccatalyst, such as high strength and durability and excellentconductivity, and a method of determining nozzle clogging in the system.

Another embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system and a method of determining nozzleclogging in the same, for reducing a thickness and size of a catalystand a size of a reactor through a high-efficiency catalyst including asupport formed of metal with a surface on which a titanium oxide (TiO₂)nanotube is formed, and a reactive metal layer including one or more ofvanadium (V) and tungsten (W) and supported on the support, to flexiblyapply equipment for removing soot, and to integrally transfer thecatalyst and the reactor during construction of the system.

Another embodiment of the present disclosure is directed to providing anexhaust gas vessel denitration system and a method of determining nozzleclogging in the same, for supporting a reactive metal layer on a supportformed of metal with a surface on which a titanium oxide (TiO₂) nanotubeis formed, using an atomic layer deposition (ALD) method to achieve highefficiency through a catalyst with a substantially maximized specificsurface area.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexplanatory and are intended to provide further explanation ofembodiments of the invention as claimed.

In one general aspect, an exhaust gas vessel denitration system includesan exhaust pipe for discharging exhaust gas including nitrogen oxidegenerated from an engine, an urea tank for storing urea, an injectingmodule including a pulse type injector for mixing the urea with heatedair to generate a reducing agent and spraying the reducing agent to theexhaust pipe according to a pulse signal, a rotation numberadjusting-type pump for supplying the urea stored in the urea tank tothe injecting module and connected to the injecting module to beoperatively associated to the injecting module to control a supplyamount of the reducing agent, a reducing agent inlet including apressure transmitter for monitoring pressure of the reducing agentbetween the injecting module and the pump, a reactor for inducing areduction reaction of exhaust gas mixed with the reducing agent anddecomposing nitrogen oxide in the exhaust gas to nitrogen and watervapor to reduce the nitrogen oxide, wherein the reducing agent inlet isconfigured in such a way that the injecting module, the pump, and thepressure transmitter are formed as a module in an integrated dosing unit(IDU) that is one physical space.

The injecting module may include a chamber in which an outlet connectedto the exhaust pipe and urea is sprayed from the injector, and acompressed air heating supply device for heating compressed air andintroducing the compressed heated air into the chamber, wherein the ureais mixed with the compressed heated air in the chamber and is changed toammonia.

The compressed air heating supply device may include a compressed airinlet for injecting the compressed air, a compressed air transfer pipefor transferring the compressed air injected through the compressed airinlet and introducing the compressed air into the chamber, and a heatingunit for heating the compressed air inside the compressed air transferpipe.

The compressed air transfer pipe may include a cooling part that is asection disposed adjacently to the injector and cools the injector bythe compressed air prior to heating, and a heating part that is disposedadjacent to the heating unit next to the cooling part to heat andtransfer the compressed air transmitted through the cooling part and tointroduce the compressed air into the chamber.

The cooling part may be formed to surround the injector.

The heating unit may be a heater disposed inside or outside the heatingpart.

The reactor may include a catalyst for inducing a reduction reaction ofexhaust gas mixed with ammonia, and a reactor with the catalystpositioned therein.

The catalyst may include a support formed of metal with a surface onwhich a titanium oxide (TiO₂) nanotube is formed, and a reactive metallayer including one or more of vanadium (V) and tungsten (W) andsupported on the support.

The support may be formed of the metal that is titanium (Ti).

The titanium oxide (TiO₂) nanotube may have a diameter of 100 to 200 nmand a length of 300 nm to 1 μm.

The support may have a thickness of 0.1 to 0.15 mm.

The support may be changed to an anatase phase via thermal treatment.

The reactive metal layer may be supported on the support using an atomiclayer deposition (ALD) method.

In another general aspect, a method of determining nozzle clogging in anexhaust gas vessel denitration system includes a) pre-drive operationfor generating and maintaining appropriate pressure prior to an engineoperation and urea spray, b) operation of determining whether an exhaustgas temperature condition for enabling SCR is satisfied, c) operation ofselecting an urea dosing amount depending on a current engine load by acontroller, d) operation of controlling opening and closing of aninjector value to perform spray under PWM control, e) operation ofcontrolling a rotation number of a dosing pump to maintain pressure ofnormal driving, and f) operation of checking a relationship between anurea spray amount and a pump rotation number.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an exhaust gas vessel denitration systemaccording to an embodiment of the present disclosure.

FIG. 2 is a diagram showing a concept of an integrated dosing unit (IDU)included in an exhaust gas vessel denitration system according to anembodiment of the present disclosure.

FIG. 3 is a diagram showing a configuration of an injecting moduleincluded in an exhaust gas vessel denitration system according to anembodiment of the present disclosure.

FIG. 4 is a diagram showing a configuration of a reactor included in anexhaust gas vessel denitration system according to an embodiment of thepresent disclosure.

FIG. 5 is a cross-sectional view of a support of a catalyst.

FIGS. 6A and 6B are cross-sectional views of cases in which a reactivemetal layer is formed on a surface of an example of a catalyst formed ofmetal and a surface of a catalyst formed of metal according to thepresent disclosure.

FIG. 7 is a flowchart showing a method of detecting nozzle cloggingusing an integrated dosing unit (IDU) according to an embodiment of thepresent disclosure

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, an exhaust gas vessel denitration system according to thepresent disclosure is described in detail with reference to theaccompanying drawings.

In an exhaust gas vessel denitration system, selective catalystreduction (SCR) may be used. Selective catalyst reduction (SCR) refers arepresentative denitration technology for reduction of nitrogen oxideusing a catalyst (platinum (Pt)-based catalyst, V₂O₅, Al₂O₃, TiO₂,Fe₂O₃, Cr₂O₃, or the like), that is, a method of reducing nitrogen oxidewith nitrogen (N₂) and water (H₂O) using ammonia (NH₃) as a reducingagent. An exhaust gas vessel denitration system using selective catalystreduction (SCR) includes an urea dosing portion and a reactor and, inthis case, the urea dosing portion sprays urea to exhaust gas dischargedfrom an engine to induce vaporization and to convert urea into ammonia,and the reactor facilitates an active reduction reaction with a catalystpositioned in the reactor using ammonia as a reducing agent.

In the foregoing exhaust gas vessel denitration system using selectivecatalyst reduction (SCR), the urea dosing portion induces vaporizationof urea in a state in which urea is sprayed to exhaust gas and, in thecase of a vessel, since engine exhaust gas has a low temperature of 180to 210° C., the urea dosing portion of the exhaust gas vesseldenitration system installed in the vessel includes a vaporizer, aburner, or the like to ensure temperature equal to or greater than 300°C., which is for vaporization and, thus, the configuration of the vesselis complicated and equipment is increased in size. An exhaust gas vesseldenitration system of a vessel may be configured in such a way that anindependent dosing module is installed for every exhaust pipe of eachengine when a plurality of engines are present in the vessel, and thisconfiguration causes inefficiency in terms of system management such asexcessive spray of urea as well as an insufficient installation space.

A catalyst prepared by mixing reactive metal such as titanium oxide(TiO₂), vanadium (V), and tungsten (W) with ceramic and sintering themixture in the form of a honeycomb is mainly used as a catalystpositioned in the reactor, and since this type of catalyst has lowphysical strength and durability, is vulnerable to moisture, and hashigh thermal conductivity, a significant time is taken to reach anactive temperature.

In this situation, a catalyst needs to be prepared to be thick to ensurethe strength and durability of the catalyst and, thus, a specificsurface area of the catalyst is lowered and reactive metal present inthe catalyst instead of a surface of the catalyst is not capable ofexhibiting an original function thereof. As a result, the size of thecatalyst needs to be increased to ensure a specific surface area and,thus, a size of the reactor is also increased to a level of 30 to 50% ofa size of an engine. The reactor is vulnerable to vibration due to lowstrength and, thus, there is a limit in that a technology with lowvibration needs to be applied to equipment for removing soot and that acatalyst needs to be separately moved during construction. Although acatalyst formed of a metal material that has excellent strength anddurability and also has excellent thermal conductivity is present, thecatalyst is expensive and, thus, economic efficiency may be too low tobe applied to large-size transportation such as a vessel.

In this situation, according to the current trends, there has been aneed to develop technologies for enhancing a structure of an urea inletby reducing an installation space in a vessel of an exhaust gas vesseldenitration system of a vessel using selective catalyst reduction (SCR)and simplifying a structure of the vessel and to enhance efficiency of acatalyst positioned in the reactor.

FIG. 1 is a diagram showing an exhaust gas vessel denitration systemaccording to an embodiment of the present disclosure. FIG. 2 is adiagram showing a concept of an integrated dosing unit (IDU) included inan exhaust gas vessel denitration system according to an embodiment ofthe present disclosure. FIG. 3 is a diagram showing a configuration ofan injecting module included in an exhaust gas vessel denitration systemaccording to an embodiment of the present disclosure. FIG. 4 is adiagram showing a configuration of a reactor included in an exhaust gasvessel denitration system according to an embodiment of the presentdisclosure.

Referring to FIGS. 1 to 4, the exhaust gas vessel denitration systemaccording to an embodiment of the present disclosure may be an exhaustgas vessel denitration system of a vessel using selective catalystreduction (SCR) and may broadly include an exhaust pipe 1, a reducingagent inlet and a reactor 5.

The exhaust pipe 1 may be a path for discharging exhaust gas includingnitrogen oxide generated in an engine E of a vessel and, in this regard,exhaust gas may be moved to the reactor 5 through the exhaust pipe 1 andmay be mixed with ammonia injected into the exhaust pipe 1 by thereducing agent inlet before reaching to the reactor 5.

In this case, when a plurality of engines are present in the vessel, theexhaust pipe 1 may be installed for every engine.

The reducing agent inlet may inject a reducing agent into the exhaustpipe 1 and the reducing agent according to the present disclosure may beammonia obtained via vaporization of urea.

The reducing agent inlet may broadly include an urea tank 31, aninjecting module 35, a pump 33, and a pressure transmitter 34.

The urea tank 31 may store urea and, in this case, selective catalystreduction (SCR) refers to a reaction for reduction of nitrogen oxide tonitrogen (N₂) and water (H₂O) using a catalyst (platinum (Pt)-basedcatalyst, V₂O₅, Al₂O₃, TiO₂, Fe₂O₃, Cr₂O₃, or the like) and may useammonia (NH₃) as a reducing agent.

According to the present disclosure, the urea may be converted intoammonia and may enter the reactor and, in this case, the urea tank 31may store urea to be converted into a reducing agent.

The injecting module 35 may include a pulse type injector 353 for mixingurea with heated air to generate a reducing agent and spraying thereducing agent to the exhaust pipe 1 according to a pulse signal.

The pump 33 may include a rotation number adjusting-type pump forpumping urea stored in an urea tank and supplying the urea to theinjecting module 35 and connected to the injecting module 35 to beoperatively associated with control of a supply amount of the reducingagent.

The pressure transmitter 34 may be configured to monitor pressure of areducing agent supplied between the injecting module 35 and the pump 33,may measure pressure of urea, and may receive measurement information ofthe measured pressure.

In this case, the reducing agent inlet may include the injecting module35, the pump 33, and the pressure transmitter 34, which are formed asone module in an integrated dosing unit (IDU) as one physical space.

That is, the reducing agent inlet may be configured in such a way that amanual valve, the pump 33, a check valve, the pressure transmitter 34,and the injecting module 35 are integrally configured as a compactintegrated dosing unit (IDU), but not a method in which the pump 33 andthe injecting module are separately configured to perform continuousinjection using a throttle valve and, thus, supply and distribution ofurea as a reducing agent may be effectively controlled.

In more detail, the integrated dosing unit (IDU) may receive a controlsignal from a PLC on a separate control board to control a rotationnumber of the pump 33 and may continuously supply urea to the injectingmodule 35 and, in this case, the pulse type injector 353 of theinjecting module 35 may supply urea in a fixed amount via a periodicopening and closing operation of a nozzle according to a pulse signal.

As described above, the integrated dosing unit (IDU) may be formed inone physical space and, in this case, one physical space is a conceptthat a certain unit is stacked and installed on a plate structure, isinstalled in a three-dimensional structure with a predetermined volume,or is collectively installed in a fluid connectable region, or includesone connector for wired and wireless communication between constituenturea elements.

The integrated dosing unit (IDU) according to the present disclosure maycontrol a rotation number of the pump 33 to continuously supply ureaand, thus, may be a concept that a rotation number of the pump 33 isadjusted to supply urea in a fixed amount corresponding to a requiredamount, differently from a typical pressurization method.

In addition to the method of controlling the rotation number of the pump33, the injector may periodically control a pulse type opening andclosing operation to spray an urea in a fixed amount from a nozzle.

However, an urea return line may also be used in consideration of thecase in which it is difficult to predict a sprayed quantity of urea orurea is not capable of being normally sprayed due to nozzle clogging orother causes.

The injecting module 35 may mix urea supplied by the pump 33 with heatedair to generate ammonia and may spray the mixture to the exhaust pipe 1and may include a chamber 351 and a compressed air heating supply device355 as well as the aforementioned injector 353.

The chamber 351 is a space in which an outlet 3511 is connected to theexhaust pipe 1 and a process of mixing urea with compressed heated airto vaporize the urea to ammonia.

The outlet 3511 may be formed as a small hole compared with the chamber351 and, since the compressed heated air and the urea are continuouslysupplied into the chamber 351, ammonia generated in the chamber 351 maybe continuously injected to the exhaust pipe 1 by internal pressure.

The compressed air heating supply device 355 may heat compressed air tointroduce the compressed air into the chamber 351.

The compressed heated air may vaporize urea injected into the chamber351 to ammonia by the pulse type injector 353, and the compressed airheating supply device 355 may include a compressed air inlet 3551, acompressed air transfer pipe and a heating unit 3555.

The compressed air inlet 3551 may provide a path for injectingcompressed air.

The compressed air transfer pipe may transfer compressed air injectedthrough the compressed air inlet 3551 to introduce the compressed airinto the chamber 351.

The compressed air transfer pipe may include a cooling part 3553 a thatis a section disposed adjacently to the pulse type injector 353 andcools the pulse type injector 353 by the compressed air prior toheating, and a heating part 3553 b that is disposed adjacent to theheating unit 3555 next to the cooling part 3553 a to heat and transferthe compressed air transmitted through the cooling part 3553 a and tointroduce the compressed air into the chamber 351.

The pulse type injector 353 includes a plastic material and, thus, maybe damaged by heat and, in this regard, the compressed air transfer pipe3553 may be arranged as described above to prevent the damage, and thecompressed air may be intensively heated immediately prior to entranceinto the chamber 351, thereby enhancing heating efficiency. The coolingpart 3553 a may be formed to surround the pulse type injector 353 foreffective cooling and, to this end, a dual-pipe structure may be used.

The heating unit 3555 may heat compressed air inside the compressed airtransfer pipe 3553.

The heating unit 3555 may include a heater disposed inside or outsidethe heating part 3553 b.

To vaporize urea to ammonia, it may be to heat the compressed air at atemperature equal to or greater than 300 to 350° C., and the heatingunit 3555 for effective heating may include two line heaters to surroundopposite sides of the heating part 3553 b.

The reactor 5 may induce a reduction reaction of exhaust gas mixed withammonia to decompose nitrogen oxide in the exhaust gas to nitrogen andwater vapor to reduce nitrogen oxide and may include a catalyst 51 and areactor 53.

The catalyst 51 may induce a reduction reaction of exhaust gas mixedwith ammonia.

The catalyst 51 may include a support 511 and a reactive metal layer513.

The support 511 may be formed of metal with a surface on which atitanium oxide (TiO₂) nanotube is formed and the metal may includetitanium (Ti).

The support may be formed by growing a titanium oxide (TiO₂) nanotube ona titanium plate via an anodic oxidation scheme using an electrolytewith a specific component such as ethylene glycol or HF, performingthermal treatment, and changing the titanium oxide (TiO₂) nanotube in anamorphous state to an anatase crystalline structure as a crystallinestructure with excellent reactivity.

Referring to FIG. 5, as seen from a sectional view of the support 511,the support 511 may have a thickness of 0.1 to 0.15 mm and a titaniumoxide (TiO₂) nanotube 511 a may have a diameter of 100 to 200 nm and alength of 300 nm to 1 μm. Considering that a honeycomb-type catalystformed of a ceramic material has a thickness of a sectional view ofabout 0.3 to 0.4 mm, the catalyst 51 may be small by 50% or greatercompared with the foregoing honeycomb-type catalyst. Since both innerand outer portions of the titanium oxide (TiO₂) nanotube 511 a are acontact surface of exhaust gas and ammonia, a specific surface area isalso very large compared with a typical catalyst, which may ensuresurface flow velocity of about 60,000 that is 6 times greater than 8,000to 10,000 that is average surface flow velocity of an example of acatalyst.

The reactive metal layer 513 may be a component that includes one ormore of vanadium (V) and tungsten (W) and is supported on the support511. The reactive metal layer 513 may include metals with catalyticactivity such as vanadium (V) and tungsten (W) in the form of V₂O₅ withcatalytic activity, may be supported on the support 511, and may becoated on a surface of the support 511, including a surface of thetitanium oxide (TiO₂) nanotube 511 a of the support 511.

The reactive metal layer 513 may be coated on the support 511 using anatomic layer deposition (ALD) method.

The catalyst illustrated in FIG. 6A is formed of a metal material andmay be formed by coating a reactive metal layer on a surface of thesupport using a wash coat method. The wash coat method is difficult interms of precise control and, thus, as shown in FIG. 6A, a reactivemetal layer C is non-uniformly coated on a surface air void S of asupport during preparation of the foregoing catalyst formed of a metalmaterial.

When the reactive metal layer 513 is coated on the support 511 using awash coat method, the titanium oxide (TiO₂) nanotube 511 a has a verysmall diameter compared with an air void S of a support formed of ametal material and, thus, the titanium oxide (TiO₂) nanotube 511 a mayclog by the reactive metal layer 513 and an effect of increasing aspecific surface area through the titanium oxide (TiO₂) nanotube 511 ais barely achieved.

To prevent this, an atomic layer deposition (ALD) method of preciselythin-film supporting a reactive metal in units of atomic layers may beused and, as such, as shown in FIG. 6B, the reactive metal layer 513 maybe formed to maintain all surface areas of the titanium oxide (TiO₂)nanotube 511 a.

The reactor 53 may be a space in which the catalyst 51 is positioned andmay be a portion for a reduction reaction in which nitrogen oxide inexhaust gas being in contact with the catalyst 51 is changed to nitrogenand water using ammonia as a reducing agent.

As described above, the catalyst 51 is a high-efficiency catalyst havinga very large specific surface area and a small thickness and, thus, maybe capable of being miniaturized.

The catalyst 51 may be formed of a metal material and may haveproperties of high strength and durability and of being resistant tomoisture. Accordingly, according to the present disclosure, the size ofthe reactor 53 may be reduced, the catalyst 51 may be integrally movedand installed with the reactor 53 during a construction procedure of asystem, and it may be possible to use equipment that generates vibrationand, thus, equipment for removing soot, to be installed inside andoutside the reactor 53, may be flexibly applied.

In addition, the exhaust gas vessel denitration system according to thepresent disclosure may further include a controller 7.

The controller 7 may control a system including the reducing agent inlet3 and the reactor 5.

The controller may be a generally called control panel in automationequipment.

FIG. 7 is a flowchart showing a method of detecting nozzle cloggingusing an integrated dosing unit (IDU) according to an embodiment of thepresent disclosure. Operation a) may be a pre-drive operation ofgenerating and maintaining appropriate pressure prior to an engineoperation and urea spray. Operation b) may be an operation ofdetermining whether an exhaust gas temperature condition for enablingSCR is satisfied. When temperature of exhaust gas is greater than about300° C., the controller may select an urea dosing amount depending on acurrent engine load in operation c), and may control opening and closingof an injector valve to perform spray under PWM control in operation d).In this case, to continuously maintain an appropriate urea injectionamount, a rotation number of a pump may be controlled to maintainpressure of a normal driving operation in operation e). During anoperation of the system according to the present disclosure, arelationship between an urea spray amount and a rotation number of apump may be checked to determine whether a nozzle clogs. In more detail,according to the present disclosure, whether a nozzle clogs may bedetermined in consideration of the following mathematical expression.

Rp1<Rp2   (Mathematical Expression 1)

Here, Rp1 is a pump rotation number when a nozzle clogs and Rp2 is apump rotation number during normal driving.

In the case of normal driving without nozzle clogging after a nozzle isopen to spray urea, when an urea spray amount is increased, pressure ata front end portion of the nozzle from which urea escapes may beremarkably reduced and, to compensate for this, a pump rotation numbermay be automatically increased to maintain an appropriate pressure by apreset program of the controller.

When the nozzle clogs, the pump rotation number is not changed, neither.For example, assuming that a required pressure condition of the nozzleis 3 bar and a pump rotation number for maintaining pressure is 100 whenthe nozzle completely clogs and that an automatically increased pumprotation number for maintaining pressure is 200 when a normal flow rateis 5 LPM, the nozzle is operated in a condition for spray of 5 LPM whenthe nozzle clogs but a pump rotation number may be maintained in 100RPM. On the other hand, when the nozzle is operated in a condition forspray of 5 LPM during a normal operation, the pump rotation number maybe 200 RPM. Accordingly, pump rotation number values in the case ofnozzle clogging and an normal operation are 100 and 200, respectivelyand, thus, a relational expression of 100<200 may be satisfied.Accordingly, according to the present disclosure, a relationship betweena spray amount condition at a nozzle and a pump rotation number may besimply monitored at any time point and, thus, a degree of nozzleclogging may be determined.

According to the present disclosure, the exhaust gas vessel denitrationsystem according to the present disclosure may advantageously simplify astructure of an exhaust gas vessel denitration system of a vessel usingselective catalyst reduction (SCR) and reduce an installation space inthe vessel.

The exhaust gas vessel denitration system according to the presentdisclosure may be configured in such a way that a reducing agent inletfor injecting a reducing agent as an integrated dosing unit (IDU) formedby integrating a pump for supplying urea via control of a rotationnumber and an injecting module using pulse spray and, thus, it may beadvantageous that components such as a flow rate control valve andvarious gages accompanied thereby are simply omitted and urea spray iseffectively controlled.

The exhaust gas vessel denitration system according to the presentdisclosure may be advantageous to supply and spray a fixed amount ofurea and to rapidly and accurately determine whether a nozzle clogs byperiodically controlling a pump rotation number and opening and closingof a pulse injector.

The exhaust gas vessel denitration system according to the presentdisclosure may be advantageous to reduce a thickness and size of acatalyst and a size of a reactor through a high-efficiency catalystincluding a support formed of metal with a surface on which a titaniumoxide (TiO₂) nanotube is formed, and a reactive metal layer includingone or more of vanadium (V) and tungsten (W) and supported on thesupport, to flexibly apply equipment for removing soot, and tointegrally transferring the catalyst and the reactor during constructionof the system.

The exhaust gas vessel denitration system according to the presentdisclosure may be configured in such a way that a reactive metal layeris supported on a support formed of metal with a surface on which atitanium oxide (TiO₂) nanotube is formed, using an atomic layerdeposition (ALD) method and, thus, may be advantageous to achieve highefficiency through a catalyst with a substantially maximized specificsurface area.

Accordingly, it will be obvious to those skilled in the art to which thepresent disclosure pertains that the present disclosure described aboveis not limited to the above-mentioned embodiments and the accompanyingdrawings, but may be variously substituted, modified, and alteredwithout departing from the scope and spirit of the present disclosure.

What is claimed is:
 1. An exhaust gas vessel denitration system,comprising: an exhaust pipe for discharging exhaust gas includingnitrogen oxide generated from an engine; an urea tank for storing urea;an injecting module including a pulse type injector for mixing the ureawith heated air to generate a reducing agent and spraying the reducingagent to the exhaust pipe according to a pulse signal; a rotation numberadjusting-type pump for supplying the urea stored in the urea tank tothe injecting module and connected to the injecting module to beoperatively associated to the injecting module to control a supplyamount of the reducing agent; a reducing agent inlet including apressure transmitter for monitoring pressure of the reducing agentbetween the injecting module and the pump; a reactor for inducing areduction reaction of exhaust gas mixed with the reducing agent anddecomposing nitrogen oxide in the exhaust gas to nitrogen and watervapor to reduce the nitrogen oxide, wherein the reducing agent inlet isconfigured in such a way that the injecting module, the pump, and thepressure transmitter are formed as a module in an integrated dosing unit(IDU) that is one physical space.
 2. The exhaust gas vessel denitrationsystem of claim 1, wherein the injecting module includes: a chamber inwhich an outlet connected to the exhaust pipe and urea is sprayed fromthe injector; and a compressed air heating supply device for heatingcompressed air and introducing the compressed heated air into thechamber, wherein the urea is mixed with the compressed heated air in thechamber and is changed to ammonia.
 3. The exhaust gas vessel denitrationsystem of claim 2, wherein the compressed air heating supply deviceincludes: a compressed air inlet for injecting the compressed air; acompressed air transfer pipe for transferring the compressed airinjected through the compressed air inlet and introducing the compressedair into the chamber; and a heating unit for heating the compressed airinside the compressed air transfer pipe.
 4. The exhaust gas vesseldenitration system of claim 3, wherein the compressed air transfer pipeincludes: a cooling part that is a section disposed adjacently to theinjector and cools the injector by the compressed air prior to heating;and a heating part that is disposed adjacent to the heating unit next tothe cooling part to heat and transfer the compressed air transmittedthrough the cooling part and to introduce the compressed air into thechamber.
 5. The exhaust gas vessel denitration system of claim 4,wherein the cooling part is formed to surround the injector.
 6. Theexhaust gas vessel denitration system of claim 4, wherein the heatingunit is a heater disposed inside or outside the heating part.
 7. Theexhaust gas vessel denitration system of claim 1, wherein the reactorincludes: a catalyst for inducing a reduction reaction of exhaust gasmixed with ammonia; and a reactor with the catalyst positioned therein.8. The exhaust gas vessel denitration system of claim 7, wherein thecatalyst includes: a support formed of metal with a surface on which atitanium oxide (TiO₂) nanotube is formed; and a reactive metal layerincluding one or more of vanadium (V) and tungsten (W) and supported onthe support.
 9. The exhaust gas vessel denitration system of claim 8,wherein the support is formed of the metal that is titanium (Ti). 10.The exhaust gas vessel denitration system of claim 9, wherein thetitanium oxide (TiO₂) nanotube has a diameter of 100 to 200 nm and alength of 300 nm to 1 μm.
 11. The exhaust gas vessel denitration systemof claim 10, wherein the support has a thickness of 0.1 to 0.15 mm. 12.The exhaust gas vessel denitration system of claim 9, wherein thesupport is changed to an anatase phase via thermal treatment.
 13. Theexhaust gas vessel denitration system of claim 12, wherein the reactivemetal layer is supported on the support using an atomic layer deposition(ALD) method.
 14. A method of determining nozzle clogging in an exhaustgas vessel denitration system, the method comprising: a) pre-driveoperation for generating and maintaining appropriate pressure prior toan engine operation and urea spray; b) operation of determining whetheran exhaust gas temperature condition for enabling SCR is satisfied; c)operation of selecting an urea dosing amount depending on a currentengine load by a controller; d) operation of controlling opening andclosing of an injector value to perform spray under PWM control; e)operation of controlling a rotation number of a dosing pump to maintainpressure of normal driving; and f) operation of checking a relationshipbetween an urea spray amount and a pump rotation number.